The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A typical motor vehicle automatic transmission includes gear elements and multiplate clutches that are selectably engageable to establish one of several forward speed ratios between the transmission input and output shafts. The input shaft is coupled to the vehicle engine through a fluid coupling such as a torque converter, and the output shaft is coupled to the vehicle drive wheels through a differential gear set.
A multiplate clutch generally includes a set of friction plates, a set of separator (or reaction) plates, and a hub, all of which are housed in a clutch case. Spline grooves in the clutch case engage with splines along the outer periphery of either the separator plates or the friction plates. Another set of spline grooves in the hub engage with splines around the inner surfaces of either the friction plates or the separator plates, i.e., whichever of the plates are not splined to the case are splined to the hub. The separator plates and the friction plates are arranged alternately so that they can be engaged or disengaged with each other.
In general the contact area between each spline and respective spline groove results in high contact stresses. It may be desirable, however, to utilize relatively thin core plates bearing friction material to contact the separator plates, which increases the contact stresses between the splines and spline grooves. Larger core plates may increase the overall size of the transmission. In additions, costs are a constant concern.